Competitive binding assays are well known and well used tools in the clinical arena. They provide a specificity and sensitivity necessary for accurate qualitative and quantitative determinations. The art is full of examples of radioimmunoassays and more recently enzyme immunoassays. In the realm of enzyme immunoassays the enzyme horseradish peroxidase is a popular tag for antibodies as it is economically attractive as well as easily attachable to antibodies. The dipstick enzyme immunoassay test is used for rapid qualitating and semiquantitating the presence of an analyte. These tests, which have become more and more popular are probably an outgrowth from the urinalysis dipstick test.